The present invention generally relates to wireless communications, and particularly relates to initializing transmit powers for secondary reverse link carriers.
In some types of wireless communication networks, mobile stations are permitted to transmit reverse link data on two or more reverse link carriers, which may be referred to as one primary reverse link carrier and one or more secondary reverse link carriers. By way of non-limiting example, the 1×-EVDO standards currently in development include multi-carrier provisions that allow for primary and secondary reverse link carriers.
Controlling transmit power represents a fundamental challenge in CDMA-based networks and other interference-limited communication systems, and such control considerations extend to transmit power initialization. That is, while channel feedback may be used between transmitters and receivers for ongoing transmit power control, such feedback generally is unavailable at the outset of transmission.
The starting or initial transmit power of a primary reverse link carrier may be set by a mobile station based on access probing procedures. However, access probing is not performed once the primary reverse link carrier is established and therefore is not available for initializing the transmit power(s) of any secondary reverse link carrier(s) used by the mobile station.
One approach to initializing the transmit power of a secondary reverse link carrier is to set its initial transmit power to the current level of the primary reverse link carrier. However, to the extent that conditions for the secondary reverse link carrier differ from those for the primary reverse link carrier, this approach may result in initializing the secondary reverse link carrier transmit power either too high, or too low. Initializing the transmit power too low reduces connection success, while initializing the transmit power too high needlessly increases interference and wastes power at the mobile station.